The present invention relates to a means to extinguish an electric arc in a separable electrical contact, and more particularly, pertains to a plug or connector system for extinguishing a direct current arc without the need for an auxiliary arc-extinguishing device or mechanism.
An electric arc is a visible, luminous plasma discharge between two electrodes that is caused by an electrical current ionizing gas in the air and jumping the gap in a circuit or between two electrodes. Any time electrical contact points are opened and closed, which is common in, for example, electrical switches, electrical circuit breakers, and other electrical contact points, they become susceptible to electric arcs. While these arcs are sometimes harnessed for useful purposes such as for heating furnaces, welding, arc lamps, and illumination in spotlights, unwanted arcs may pose a dangerous risk. For example, unwanted electric arcs may cause intense heat and electric sparks, which could potentially start a fire.
An electric are may be created by both alternating current (AC) and direct current (DC) circuits. When electrical contacts carrying AC or DC are drawn apart, strong electric forces draw electrons from one electrode to the other, and an arc is created. Extinguishing an AC arc is relatively simple compared to extinguishing a DC arc. When contacts transmitting AC are parted, an AC arc is created but quickly extinguished by virtue of the next voltage zero that occurs when the electric charge reverses direction. However, rupturing a DC arc is more difficult since the electric charge is unidirectional and there are no zero voltages to automatically extinguish the arc.
Various methods for extinguishing a DC arc have been attempted in the prior art. Some of these methods utilize a magnetic coil or permanent magnet to interact with the arc, taking advantage of the arc's magnetic properties. For example, blowout coils may be used to stretch the arc column until the arc ruptures. Or, a magnetic blast may be used to quickly extinguish the arc in a single blow. However, these magnetic methods are only successful at relatively high current levels, and the requisite amplitude of the magnetic fields generally requires very strong magnets, for example, expensive rare-earth magnets such as Sm2Co17 or NdFeB. In an alternative method, the arc may be immersed in transformer oil, dielectric gas, or a vacuum to suppress or quench the are. Other known methods utilize basic mechanical means, such as blades, knives, or even 12-gauge shotgun shell blasts to extinguish the arc. However, these demanding methods rely upon external sources that are expensive and inconvenient to use.
With the current existing methods, externally derived forces are needed to extinguish the DC arc, whether magnetic, mechanical, or otherwise. The present invention seeks to improve upon such prior art by providing a means to extinguish a DC arc in a separable electrical contact without the need for externally-derived forces in a method integrated with the connector apparatus itself.
Additional features of the present invention seek to facilitate the extinguishment of a DC arc by limiting arc formation to discrete locations of contact between connectors. Also, a safe and inexpensive means which does not reply upon external components is desired.